scholarly journals Polymer degradation: a short review

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jiří Vohlídal
Keyword(s):  
Thermal Degradation ◽  
Oxidative Degradation ◽  
Polymer Degradation ◽  
Short Review ◽  
Basic Knowledge ◽  
Photochemical Degradation ◽  
Polymer Recycling ◽  
Kinetics Of ◽  
Mechanochemical Degradation

AbstractThe reader will find basic knowledge about the degradation of polymers, its causes, course and consequences in a broader context, as indicated through the list of the chapter titles: Introduction; Depolymerization; Initiated cleavage (degradation) of macromolecules; Thermal degradation; Photochemical degradation; Mechanochemical degradation; Oxidative degradation; Polymer burning; Kinetics of cleaving macromolecules when chain depolymerization is negligible; Degradation in polymer recycling; Protection of polymers against degradation.

Kinetics of thermal degradation and thermal oxidative degradation of poly(p-dioxanone)

2003 ◽  
Vol 39 (8) ◽  
pp. 1567-1574 ◽  
Author(s):  
Ke-Ke Yang ◽  
Xiu-Li Wang ◽  
Yu-Zhong Wang ◽  
Bo Wu ◽  
Yong-Dong Jin ◽  
...  
Keyword(s):  
Thermal Degradation ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Kinetics Of

Basic Knowledge Models for the Processing of Bread as a Solid Foam

2014 ◽  
Vol 611-612 ◽  
pp. 901-908 ◽  
Author(s):  
Guy della Valle ◽  
Hubert Chiron ◽  
Lucio Cicerelli ◽  
Kamal Kansou ◽  
Kati Katina ◽  
...  
Keyword(s):  
Short Review ◽  
Operating Conditions ◽  
Basic Knowledge ◽  
Output Variable ◽  
Knowledge Models ◽  
Alveolar Structure ◽  
Solid Foam ◽  
Baked Products ◽  
Input Variables ◽  
Kinetics Of

The breadmaking process can be defined by the succession of operations with operating conditions as input variables and dough properties as output ones, any output variable at step i being an input at step i+1. In this paper, we strive to show how the main properties of bread, density, porosity and alveolar structure (crumb), can be predicted from basic knowledge models (BKMs). So we have defined the variables of breadmaking, proposed BKMs for the two first operations, mixing and proofing, and underlined the needs to define them for shaping and baking, after a short review of existing models. The specific energy delivered during mixing is determined by a simple balance equation in order to predict gluten structuration and dough viscosity, the main output of mixing operation. Then an analysis of dough proofing at different structural scales, by rheology and imaging, allows to assess its alveolar structure, and to fit the kinetics of porosity and stability by phenomenological models. Finally we show how these BKMs could be integrated in order to help the design of baked products with target properties.

scholarly journals Thermal Degradation Kinetics and Modeling Study of Ultra High Molecular Weight Polyethylene (UHMWP)/Graphene Nanocomposite

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1597
Author(s):  
Iman Jafari ◽  
Mohamadreza Shakiba ◽  
Fatemeh Khosravi ◽  
Seeram Ramakrishna ◽  
Ehsan Abasi ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Thermal Degradation ◽  
High Molecular Weight ◽  
Degradation Kinetics ◽  
Graphene Nanosheets ◽  
Thermal Degradation Kinetics ◽  
Graphene Nanocomposites ◽  
Kinetics Of ◽  
Ultra High Molecular Weight

The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (Ea) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.

scholarly journals Thermal Degradation Kinetics of Sugarcane Bagasse and Soft Wood Cellulose

Materials ◽  
2017 ◽  
Vol 10 (11) ◽  
pp. 1246 ◽  
Author(s):  
Samson M. Mohomane ◽  
Tshwafo E. Motaung ◽  
Neerish Revaprasadu
Keyword(s):  
Thermal Degradation ◽  
Sugarcane Bagasse ◽  
Degradation Kinetics ◽  
Thermal Degradation Kinetics ◽  
Wood Cellulose ◽  
Kinetics Of
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